(Al 'Arifin/'Urufa). They see and recognize Allah wherever they look. The knowers are bewildered. But this is not the bewilderment of being lost, rather it is the bewilderment of having found Allah. They know that He cannot be known. The knowers are nothing because they are everything.
(Hudur) is the heart's presence with Allah when it is absent from everything else. The slave can never be present with Allah except through one of His Beautiful Names and in so doing a state of perfect spiritual courtesy is maintained.
(Kashf). Unveiling or revelation is one of the types of direct experience through which Knowledge of Reality is unveiled to the heart of the slave and lover. In His Infinite Grace Allah gives His slave and lover a Divine Self-disclosure which not only increases his Knowledge of Allah but also increases his yearning and intense love of Allah. The great Sufis are called The People of Unveiling and Finding. Within the unveiling they find Allah. This unveiling and finding frequently occurs during the spiritual concert. In a moment, when it is perceived through unveiling that 'Allah is the singer and Allah is the hearer', the singer and the hearer become One, disappearing into Allah.
(Al Muhaqqiqun). These great ones form the highest category of friends of Allah. They follow no one's authority because in themselves they have verified and realized [through unveiling and finding], the truth and reality of all things which is Allah, the Real. They are also known as'The People of Unveiling and Finding'.